content: /*
   * Copyright 2016-present David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.rxjava3.basetypes;
  
  import java.util.Objects;
  import java.util.concurrent.atomic.AtomicReference;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.*;
  import io.reactivex.rxjava3.internal.subscriptions.*;
  
  /**
   * Map the signals of the upstream into a Perhaps and emit
   * its signals.
   *
   * @param <T> the upstream value type
   * @param <R> the result value type
   */
  final class PerhapsFlatMapSignal<T, R> extends Perhaps<R> {
  
      final Perhaps<T> source;
  
      final Function<? super T, ? extends Perhaps<? extends R>> onSuccessMapper;
  
      final Function<? super Throwable, ? extends Perhaps<? extends R>> onErrorMapper;
  
      final Supplier<? extends Perhaps<? extends R>> onCompleteMapper;
  
      PerhapsFlatMapSignal(Perhaps<T> source,
              Function<? super T, ? extends Perhaps<? extends R>> onSuccessMapper,
              Function<? super Throwable, ? extends Perhaps<? extends R>> onErrorMapper,
                      Supplier<? extends Perhaps<? extends R>> onCompleteMapper
     ) {
          this.source = source;
          this.onSuccessMapper = onSuccessMapper;
          this.onErrorMapper = onErrorMapper;
          this.onCompleteMapper = onCompleteMapper;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super R> s) {
          source.subscribe(new FlatMapSubscriber<T, R>(s, onSuccessMapper, onErrorMapper, onCompleteMapper));
      }
  
      static final class FlatMapSubscriber<T, R> extends DeferredScalarSubscription<R>
      implements Subscriber<T> {
  
          private static final long serialVersionUID = 1417117475410404413L;
  
          final Function<? super T, ? extends Perhaps<? extends R>> onSuccessMapper;
  
          final Function<? super Throwable, ? extends Perhaps<? extends R>> onErrorMapper;
  
          final Supplier<? extends Perhaps<? extends R>> onCompleteMapper;
  
          final InnerSubscriber inner;
  
          Subscription upstream;
  
          boolean hasValue;
  
          FlatMapSubscriber(Subscriber<? super R> downstream,
                  Function<? super T, ? extends Perhaps<? extends R>> onSuccessMapper,
                          Function<? super Throwable, ? extends Perhaps<? extends R>> onErrorMapper,
                                  Supplier<? extends Perhaps<? extends R>> onCompleteMapper) {
              super(downstream);
              this.onSuccessMapper = onSuccessMapper;
              this.onErrorMapper = onErrorMapper;
              this.onCompleteMapper = onCompleteMapper;
              this.inner = new InnerSubscriber();
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
  
                  downstream.onSubscribe(this);
  
                  s.request(Long.MAX_VALUE);
              }
          }
  
          @Override
          public void onNext(T t) {
              hasValue = true;
              Perhaps<? extends R> ph;
  
              try {
                  ph = Objects.requireNonNull(onSuccessMapper.apply(t), "The onSuccessMapper returned a null Perhaps");
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  downstream.onError(ex);
                  return;
              }
  
              ph.subscribe(inner);
          }
  
          @Override
          public void onError(Throwable t) {
              Perhaps<? extends R> ph;
              try {
                  ph = Objects.requireNonNull(onErrorMapper.apply(t), "The onErrorMapper returned a null Perhaps");
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  downstream.onError(ex);
                  return;
              }
              ph.subscribe(inner);
          }
  
          @Override
          public void onComplete() {
              if (!hasValue) {
                  Perhaps<? extends R> ph;
                  try {
                      ph = Objects.requireNonNull(onCompleteMapper.get(), "The onCompleteMapper returned a null Perhaps");
                  } catch (Throwable ex) {
                      Exceptions.throwIfFatal(ex);
                      downstream.onError(ex);
                      return;
                  }
                  ph.subscribe(inner);
              }
          }
  
          void innerNext(R t) {
              value = t;
          }
  
          void innerError(Throwable ex) {
              downstream.onError(ex);
          }
  
          void innerComplete() {
              R v = value;
              if (v != null) {
                  complete(v);
              } else {
                  downstream.onComplete();
              }
          }
  
          @Override
          public void cancel() {
              super.cancel();
              upstream.cancel();
              SubscriptionHelper.cancel(inner);
          }
  
          final class InnerSubscriber extends AtomicReference<Subscription>
          implements Subscriber<R> {
  
              private static final long serialVersionUID = -7349825169192389387L;
  
              @Override
              public void onSubscribe(Subscription s) {
                  if (SubscriptionHelper.setOnce(this, s)) {
                      s.request(Long.MAX_VALUE);
                  }
              }
  
              @Override
              public void onNext(R t) {
                  innerNext(t);
              }
  
              @Override
              public void onError(Throwable t) {
                  innerError(t);
              }
  
              @Override
              public void onComplete() {
                  innerComplete();
              }
          }
      }
  }
  